U.S. patent application number 11/192151 was filed with the patent office on 2006-02-02 for durable glass and glass enamel composition for glass coatings.
This patent application is currently assigned to Shepherd Color Company. Invention is credited to Hasan B. Emlemdi.
Application Number | 20060025298 11/192151 |
Document ID | / |
Family ID | 35733099 |
Filed Date | 2006-02-02 |
United States Patent
Application |
20060025298 |
Kind Code |
A1 |
Emlemdi; Hasan B. |
February 2, 2006 |
Durable glass and glass enamel composition for glass coatings
Abstract
The present invention provides glass compositions and glass
coating systems for use on glass substrates in several industrial
applications. It relates to a lead-free and cadmium-free glass
enamel coating made primarily by utilizing at least one or more of
lead-free and cadmium-free glass compositions comprising in weight
percent from about 26% to about 63% SiO.sub.2, from about 2% to
about 10.5% ZnO, from about 8% to about 20% B.sub.2O.sub.3, from
about 0.1% to about 10% Bi.sub.2O.sub.3, up to about 12% Na.sub.2O,
from about 0.1% to about 17% K.sub.2O, up to about 6% Li.sub.2O,
from about 0.1% to about 22% of Ta.sub.2O.sub.5, from about 0.0% to
about 22% of Nb.sub.2O.sub.5, up to about 8% from each of
Al.sub.2O.sub.3, TiO.sub.2, ZrO.sub.2, BaO and SrO, from about 0.1%
to about 7% Sb.sub.2O.sub.3, up to about 7% F.sub.2, up to about 4%
from each of CaO, Mo.sub.2O.sub.3 and MgO, and from about 0.1% to
about 4% of one or more of La.sub.2O.sub.3, Nd.sub.2O.sub.3,
Pr.sub.2O.sub.3 and Ce.sub.2O.sub.3.
Inventors: |
Emlemdi; Hasan B.;
(Hamilton, OH) |
Correspondence
Address: |
FROST BROWN TODD, LLC
2200 PNC CENTER
201 E. FIFTH STREET
CINCINNATI
OH
45202
US
|
Assignee: |
Shepherd Color Company
|
Family ID: |
35733099 |
Appl. No.: |
11/192151 |
Filed: |
July 28, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60592457 |
Jul 30, 2004 |
|
|
|
Current U.S.
Class: |
501/26 ; 501/64;
501/65; 501/78; 501/79 |
Current CPC
Class: |
C03C 8/04 20130101; C03C
17/04 20130101; C03C 8/14 20130101 |
Class at
Publication: |
501/026 ;
501/064; 501/065; 501/078; 501/079 |
International
Class: |
C03C 8/04 20060101
C03C008/04; C03C 3/066 20060101 C03C003/066; C03C 3/068 20060101
C03C003/068; C03C 3/089 20060101 C03C003/089; C03C 3/095 20060101
C03C003/095 |
Claims
1. A lead-free glass frit comprising in percent by weight from
about 26% to about 63% SiO.sub.2, from about 2% to about 10.5% ZnO,
from about 8% to about 20% B.sub.2O.sub.3, from about 0.1% to about
10% Bi.sub.2O.sub.3, up to about 12% Na.sub.2O, from about 0.1% to
about 17% K.sub.2O, up to about 6% Li.sub.2O, from about 0.1% to
about 22% of Ta.sub.2O.sub.5, from about 0% to about 22% of
Nb.sub.2O.sub.5, up to about 8% from each of Al.sub.2O.sub.3,
TiO.sub.2, ZrO.sub.2, BaO and SrO, from about 0.1% to about 7%
Sb.sub.2O.sub.3, up to about 7% F, up to about 4% from each of CaO,
Mo.sub.2O.sub.3 and MgO, and from about 0.1% to about 4% of one or
more of La.sub.2O.sub.3, Nd.sub.2O.sub.3, Pr.sub.2O.sub.3 or
Ce.sub.2O.sub.3.
2. The lead-free glass frit composition according to claim 1
comprising in percent by weight from about 28% to about 60%
SiO.sub.2, from about 3% to about 10.5% ZnO, from about 9% to about
19% B.sub.2O.sub.3, up to about 8% Na.sub.2O, up to about 6% from
each of BaO, SrO, Al.sub.2O.sub.3, TiO.sub.2 and ZrO.sub.2, from
about 0.1% to about 15% K.sub.2O, from about 0.1% to about 7%
Bi.sub.2O.sub.3, from about 0.25% to about 4.5% Li.sub.2O, from
about 0% to about 16% from each of Nb.sub.2O.sub.5 and
Ta.sub.2O.sub.5, up to about 5% F, from about 0.1% to about 5%
Sb.sub.2O.sub.3, up to about 3% from each of CaO, Mo.sub.2O.sub.3
and MgO, and from about 0.1% to about 3% of one or more of
La.sub.2O.sub.3, Nd.sub.2O.sub.3, Pr.sub.2O.sub.3 or
Ce.sub.2O.sub.3.
3. The lead-free glass frit composition according to claim 2
comprising in percent by weight from about 30% to about 56%
SiO.sub.2, from about 4% to about 10% ZnO, from about 10% to about
18% B.sub.2O.sub.3, from about 0.1% to about 5% from each of
Na.sub.2O, Al.sub.2O.sub.3, TiO.sub.2 and ZrO.sub.2, from about
0.25% to about 13.5% K.sub.2O, from about 0.25% to about 3%
Bi.sub.2O.sub.3, from about 0.5% to about 3% Li.sub.2O, from about
0.25% to about 11% of Ta.sub.2O.sub.5, from about 0% to about 11%
Nb.sub.2O.sub.5, up to about 4% from each of BaO and SrO, from
about 0.25% to about 3.5% Sb.sub.2O.sub.3, from about 0.1% to about
3.5% F, up to about 2% from each of CaO, Mo.sub.2O.sub.3 and MgO,
and from about 0.25% to about 2% of one or more of La.sub.2O.sub.3,
Nd.sub.2O.sub.3, Pr.sub.2O.sub.3 or Ce.sub.2O.sub.3.
4. The glass frit according to claim 1 which includes from about
0.25% to about 11% Ta.sub.2O.sub.5.
5. The glass frit according to claim 1 which is substantially free
of Nb.sub.2O.sub.5.
6. The glass frit according to claim 3 which is substantially free
of Nb.sub.2O.sub.5.
7. The glass frit according to claim 1 which includes from about
0.25% to about 3% Bi.sub.2O.sub.3.
8. The glass frit according to claim 3 which has a coefficient of
thermal expansion of from about 65.times.10.sup.-7/.degree. C. to
about 90.times.10.sup.-7/.degree. C.
9. A glass enamel composition comprising the glass frit composition
according to claim 1.
10. A glass enamel composition comprising the glass frit
composition according to claim 3.
11. A glass enamel composition comprising the glass frit
composition according to claim 4.
12. A glass enamel composition comprising the glass frit
composition according to claim 5.
13. A glass enamel composition comprising the glass frit
composition according to claim 7.
14. A glass enamel composition comprising the glass frit
composition according to claim 4 together with a medium selected
from water miscible media, thermoplastic media, spray media, roller
coater media, pad transfer media, UV curable media, and mixtures
thereof.
15. A glass enamel composition comprising the glass frit
composition according to claim 1 together with a medium selected
from water miscible media, thermoplastic media, spray media, roller
coater media, pad transfer media, UV curable media, and mixtures
thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This patent application is based upon and claims priority
from U.S. Provisional Patent Application 60/592,457, Emlemdi, filed
Jul. 30, 2004, incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention provides a new and improved durable
environmentally friendly glass enamel system for glass
coatings.
BACKGROUND OF THE INVENTION
[0003] Numerous glass enamel compositions that are lead-free and
cadmium-free are known in the prior art.
[0004] In general, lead free glasses and lead free glass enamel
compositions for glass coating systems reported in the prior art
and prior literature can be categorized into two major, however
rather broad, groups that are of interest to illustrate the
importance and progression of the present invention. One group is
often characterized as zinc-boro-silicate glasses. These types of
glasses, even the ones claiming improved durability are often
weaker in weathering the elements than their lead-containing
counterparts. The other major group can be distinguished by its
significant bismuth content. It is, therefore, very costly to
produce this latter group, even though this group is often
characterized as being better performing glass enamels. It is known
to people familiar with these types of products that for decades
the above-mentioned two major categories have been intended to
displace the more forgiving, usually better performing,
lead-containing materials which are now being phased out due to
environmental and regulatory pressure.
[0005] An example of a prior art lead-free glass enamel may be
found in Francel et al., U.S. Pat. No. 4,537,862, issued Aug. 27,
1985. Francel et al. discloses a glass enamel including a frit
comprising by weight 25-32% SiO.sub.2, 25-32% B.sub.2O.sub.3,
10-18% ZrO.sub.2, 0-9% Na.sub.2O, 0-5% K.sub.2O, 0-9% Li.sub.2O,
0-2% SnO.sub.2, 0-3% CaO, 0-6% SrO, and 10-18% rare earth oxide,
wherein the ratio of ZrO.sub.2 to rare earth oxide is about 1:1 to
1.4:1, the amount of ZrO.sub.2 plus rare earth oxide is about 20%
to 33%, and the amount of Li.sub.2O, K.sub.2O and Na.sub.2O is
about 1% to 10%. Another example of a prior art lead-free glass
enamel may be found in Roberts, U.S. Pat. No. 4,859,637, issued
Aug. 22, 1989. Roberts discloses a lead-free glass enamel including
a frit comprising by weight 19-45% SiO.sub.2, 20-33%
B.sub.2O.sub.3, 0-10% ZrO.sub.2, 8-15% alkali metal oxide, 0-35%
ZnO, 0-6% Al.sub.2O.sub.3, 0-3% BaO, 0-8% P.sub.2O.sub.5, 0-6%
La.sub.2O.sub.3, and 2-10% F.sub.2. Klimas et al., in U.S. Pat. No.
4,970,178, issued Nov. 13, 1990, teaches the inclusion of
Bi.sub.2O.sub.3 in a lead-free glass enamel/glaze including a frit
comprising by mole 45-60% SiO.sub.2, 6-13% B.sub.2O.sub.3, 0-6%
ZrO.sub.2, 5-14% Na.sub.2O, 0-8% K.sub.2O, 0.0-5% Li.sub.2O, 8-25%
ZnO, 0-8% CaO, 0-8% SrO, 0-10% Bi.sub.2O.sub.3, 0-4%
Al.sub.2O.sub.3, 0-9% BaO, 0-7% TiO.sub.2, and 0-1% WO.sub.3.
[0006] Another example of a prior art lead-free glass enamel may be
found in Emlemdi et al., U.S. Pat. No. 5,504,045, issued Apr. 2,
1996. Emlemdi et al. teaches that excellent scratch resistance and
other desirable properties can be attained by a lead-free glass
enamel including a frit comprising by mole 8.5-15.6% SiO.sub.2,
27.4-36.45% B.sub.2O.sub.3, 7.5-12.1% Na.sub.2O, 1.2-2.4% K.sub.2O,
0.0% Li.sub.2O, 1-2.6% MgO, 3.4-5.5% CaO, 0.5-1.4% SrO, 28.1-38.5%
ZnO, 0.6-1.9% Al.sub.2O.sub.3, 0.9-2.2% P.sub.2O.sub.5, and
2.6-4.3% F.sub.2. A more recent example of a prior art lead-free
glass enamel may be found in Kniajer et al., U.S. Pat. No.
6,346,493, issued Feb. 12, 2002. Kniajer et al. discloses a
lead-free glass enamel including a frit comprising by weight 28-60%
SiO.sub.2, 9-21% B.sub.2O.sub.3, 0-11% ZrO.sub.2, 0-15% Na.sub.2O,
0-13% K.sub.2O, 0-6% Li.sub.2O, 5-22% ZnO, 0-5% CaO, 0-2% MgO, 0-8%
SrO, 0-9% Bi.sub.2O.sub.3, 0-6% Al.sub.2O.sub.3, 0-20%
Nb.sub.2O.sub.5, 0-25% TiO.sub.2, 0-12% BaO, 0-6% Sb.sub.2O.sub.3,
0-5% LnOx, and 0-6% F.sub.2.
SUMMARY OF THE INVENTION
[0007] In addition to being a lead-free and cadmium-free glass frit
and glass enamel composition, the present invention is unique in
the fact that it contains minimum amounts of Bi.sub.2O.sub.3 giving
this invention the overall added benefit of cost reduction.
Furthermore, this invention introduces the benefit of adding
Ta.sub.2O.sub.5 into the mainly zinc-borosilicate glass
formulations. Those formulations are also characterized by
containing minimal amounts of Bi.sub.2O.sub.3, in addition to the
rest of the specified ingredients.
[0008] The glass component in the present invention includes one or
more glass frits containing, in weight percent, from about 26% to
about 63% SiO.sub.2, from about 2% to about 10.5% ZnO, from about
8% to about 20% B.sub.2O.sub.3, from about 0.1% to about 10%
Bi.sub.2O.sub.3, up to about 12% Na.sub.2O, from about 0.1% to
about 17% K.sub.2O, up to about 6% Li.sub.2O, from about 0.1% to
about 22% of Ta.sub.2O.sub.5, from about 0% to about 22% of
Nb.sub.2O.sub.5, up to about 8% from each of Al.sub.2O.sub.3,
TiO.sub.2, ZrO.sub.2, BaO and SrO, from about 0.1% to about 7%
Sb.sub.2O.sub.3, up to about 7% F.sub.2, up to about 4% from each
of CaO, Mo.sub.2O.sub.3 and MgO, and from about 0.1% to about 4% of
one or more of La.sub.2O.sub.3, Nd.sub.2O.sub.3, Pr.sub.2O.sub.3
and Ce.sub.2O.sub.3.
[0009] In an intermediate range, the glass component in this
invention includes one or more glass frits containing, in weight
percent, from about 28% to about 60% SiO.sub.2, from about 3% to
about 10.5% ZnO, from about 9% to about 19% B.sub.2O.sub.3, up to
about 8% Na.sub.2O, up to about 6% from each of BaO, SrO,
Al.sub.2O.sub.3, TiO.sub.2 and ZrO.sub.2, from about 0.1% to about
15% K.sub.2O, from about 0.1% to about 7% Bi.sub.2O.sub.3, from
about 0.25% to about 4.5% Li.sub.2O, from about 0.1% to about 16%
of Ta.sub.2O.sub.5, from about 0% to about 16% of Nb.sub.2O.sub.5,
up to about 5% F.sub.2, from about 0.1% to about 5%
Sb.sub.2O.sub.3, up to about 3% from each of CaO, Mo.sub.2O.sub.3
and MgO, and from about 0.1% to about 3% of one or more of
La.sub.2O.sub.3, Nd.sub.2O.sub.3, Pr.sub.2O.sub.3 and
Ce.sub.2O.sub.3.
[0010] In a more preferred range, the glass component in this
invention includes one or more glass frits containing, in weight
percent, from about 30% to about 56% SiO.sub.2, from about 4% to
about 10% ZnO, from about 10% to about 18% B.sub.2O.sub.3, from
about 0.1% to about 5% from each of Na.sub.2O, Al.sub.2O.sub.3,
TiO.sub.2 and ZrO.sub.2, from about 0.25% to about 13.5% K.sub.2O,
from about 0.25% to about 3% Bi.sub.2O.sub.3, from about 0.5% to
about 3% Li.sub.2O, from about 0.25% to about 11% of
Ta.sub.2O.sub.5, from about 0% to about 11% of Nb.sub.2O.sub.5, up
to about 4% from each of BaO and SrO, from about 0.25% to about
3.5% Sb.sub.2O.sub.3, from about 0.1% to about 3.5% F.sub.2, up to
about 2% from each of CaO, Mo.sub.2O.sub.3 and MgO, and from about
0.25% to about 2% of one or more of La.sub.2O.sub.3,
Nd.sub.2O.sub.3, Pr.sub.2O.sub.3 and Ce.sub.2O.sub.3.
[0011] In each of these broad, intermediate and more preferred
ranges, the products of this invention may include the coloring
oxides (including but not limited to CuO, CO.sub.2O.sub.3,
MnO.sub.2, Fe.sub.2O.sub.3, NiO, Cr.sub.2O.sub.3, V.sub.2O.sub.5)
as an optional addition to give colors other than the more popular
lighter colors. The ranges at which these materials are generally
used are set forth in the attached table.
DETAILED DESCRIPTION OF THE INVENTION
[0012] This invention relates to a glass enamel coating system that
exhibits excellent acid resistance, good adhesion to glass
substrates, and a clear texture allowing it to be colored at will
by utilizing the desired/adequate pigmentation. The materials also
have a functional maturation temperature and a substrate-compatible
coefficient of thermal expansion.
[0013] The present invention includes small amounts of
Bi.sub.2O.sub.3, from about 0.1% to about 10% Bi.sub.2O.sub.3 in
the broad range, and from about 0.25% to about 3% Bi.sub.2O.sub.3
in the more preferred range. This provides the added advantage of a
more cost-effective glass enamel. More significantly, this
invention is a pioneer in the utilization of Ta.sub.2O.sub.5 in the
lead-free and cadmium-free glass frits and glass enamel
compositions to provide several desirable properties. An important
aspect of this invention is the discovery that the inclusion of
tantalum oxide or other sources of tantalum oxide in the
compositions of the present invention at from about 0.1% to about
22% Ta.sub.2O.sub.5 in the broad range, and from about 0.25% to
about 11% Ta.sub.2O.sub.5 in the more preferred range results in
improved properties. It must be noted that not much Ta.sub.2O.sub.5
is needed to enhance the glass properties, thus maintaining the
advantage of a more cost-effective glass enamel. Without intending
to be bound by theory, it is believed that the presence of the
tantalum oxide provides a strengthening of the resultant glass
enamel presumably via inhibiting the migration of mobile
species.
[0014] The glass frit compositions that are lead-free and
cadmium-free utilized for glass enamel coating systems according to
the present invention have the added advantages of being more
durable, clearer, glossier, and slightly softer than conventional
glass enamel coatings. Moreover, this invention teaches that
suitable and durable glass can be attained even without the
incorporation of Nb.sub.2O.sub.5, provided the other defined
components of the present invention are utilized. This is in
contrast to recent work done on similar and non similar systems
utilizing Nb.sub.2O.sub.5. Thus, preferred compositions of the
present invention are substantially free of Nb.sub.2O.sub.5.
[0015] A glass frit or glass frits made in accordance with the
principles of the present invention are processed according to the
established art of frit making. This means that a frit according to
this invention can be prepared by mixing together the proper raw
materials which are, individually, well known to those skilled in
the art. The raws are then melted in a furnace prepared for glass
making or in sintered fused silica crucibles at temperatures
between about 2000.degree. F. (1090.degree. C.) and about
2250.degree. F. (1230.degree. C.), for about 1 hour. The exact
smelting time largely depends on the batch size. Attention should
also be paid to fluorine volatilization. The molten glass can be
quenched into a water pool with the help of a stream of water,
which is known as "water quench" process, or quenched through two
water-cooled metal drums which is known as "roll quench" process.
The product frits are then ground and dried into a suitable average
particle size dry flux. Such techniques are well known to those
skilled in the art.
[0016] This invention relates to unique lead-free glass frits. The
compositions which these materials generally have are set forth in
the following table: TABLE-US-00001 INTER- BROAD RANGE MEDIATE
PREFERRED from to from to from to about about about about about
about Li.sub.2O Lithium 0.00 6.00 0.25 4.50 0.50 3.00 oxide
K.sub.2O Potassium 0.10 17.00 0.10 15.00 0.25 13.50 oxide Na.sub.2O
Sodium 0.00 12.00 0.00 8.00 0.10 5.00 oxide CaO Calcium 0.00 4.00
0.00 3.00 0.00 2.00 oxide MgO Magnesium 0.00 4.00 0.00 3.00 0.00
2.00 oxide SrO Strontium 0.00 8.00 0.00 6.00 0.00 4.00 oxide BaO
Barium 0.00 8.00 0.00 6.00 0.00 4.00 oxide ZnO Zinc 2.00 13.00 3.00
13.00 4.00 10.50 oxide Al.sub.2O.sub.3 Alumina 0.00 8.00 0.00 6.00
0.10 5.00 oxide B.sub.2O.sub.3 Boron 8.00 20.00 9.00 19.00 10.00
18.00 trioxide Sb.sub.2O.sub.3 Antimony 0.10 7.00 0.10 5.00 0.25
3.50 trioxide SiO.sub.2 Silica 26.00 63.00 28.00 60.00 30.00 56.00
TiO.sub.2 Titanium 0.00 8.00 0.00 6.00 0.10 5.00 dioxide ZrO.sub.2
Zirconium 0.00 8.00 0.00 6.00 0.10 5.00 dioxide F.sub.2 Fluorine
0.00 7.00 0.00 5.00 0.10 3.50 Bi.sub.2O.sub.3 Bismuth 0.10 10.00
0.10 7.25 0.25 3.00 trioxide Ta.sub.2O.sub.5 Tantalum 0.10 22.00
0.10 16.00 0.25 11.00 oxide Nb.sub.2O.sub.5 Niobium 0.00 22.00 0.00
16.00 0.00 11.00 oxide Mo.sub.2O.sub.3 Molybdenum 0.00 4.00 0.00
3.00 0.00 2.00 trioxide Ce.sub.2O.sub.3 Cerium 0.10 4.00 0.10 3.00
0.25 2.00 oxide* Nd.sub.2O.sub.5 Neodymium trioxide*
La.sub.2O.sub.3 Lanthanum oxide* Pr.sub.2O.sub.3 Praseo- dymium
trioxide* V.sub.2O.sub.5 Vanadium 0.00 6.00 0.10 4.00 0.25 2.00
pentoxide** Cr.sub.2O.sub.3 Chromium oxide** MnO.sub.2 Manganese
dioxide** Co.sub.2O.sub.3 Cobalt oxide** CuO Copper oxide**
Fe.sub.2O.sub.3 Iron oxide** NiO Nickel oxide** *Required
additional oxide **Optional additional coloring oxide
[0017] The following formulations are examples of glass enamel frit
compositions of this invention. They are intended to be exemplary
only and are not limiting of the scope of the present invention.
TABLE-US-00002 FORMULATIONS Example 1 Example 2 Example 3 Example 4
Li.sub.2O Lithium 2.80 2.80 0.00 0.00 oxide K.sub.2O Potassium
12.50 13.15 6.50 13.00 oxide Na.sub.2O Sodium oxide 0.25 0.00 10.00
5.00 MgO Magnesium 0.10 0.00 0.00 0.00 oxide SrO Strontium 0.10
0.00 0.00 0.00 oxide ZnO Zinc oxide 12.00 10.40 12.00 12.00
Al.sub.2O.sub.3 Alumina oxide 0.10 0.15 0.10 0.15 B.sub.2O.sub.3
Boron 13.00 13.50 13.50 13.00 trioxide Sb.sub.2O.sub.3 Antimony
1.75 1.90 0.15 0.25 trioxide SiO.sub.2 Silica 51.00 53.80 53.40
52.50 TiO.sub.2 Titanium 2.75 2.90 0.00 0.00 dioxide F.sub.2
Fluorine 0.10 0.10 2.75 3.00 Bi.sub.2O.sub.3 Bismuth 0.75 0.75 1.25
0.55 trioxide Ta.sub.2O.sub.5 Tantalum 2.50 0.25 0.25 0.25 oxide
Ce.sub.2O.sub.3 Cerium oxide 0.30 0.30 0.10 0.30 Nd.sub.2O.sub.3
Neodymium trioxide La.sub.2O.sub.3 Lanthanum oxide Pr.sub.2O.sub.3
Praseodymium trioxide V.sub.2O.sub.5 Vanadium 0.00 0.00 0.00 0.00
pentoxide Cr.sub.2O.sub.3 Chromium oxide MnO.sub.2 Manganese oxide
Co.sub.2O.sub.3 Cobalt oxide CuO Copper oxide Fe.sub.2O.sub.3 Iron
oxide NiO Nickel oxide Total 100.00 100.00 100.00 100.00
[0018] This invention allows for glass frit(s) with suitable
coefficient of thermal expansion (CTE) from about
65.times.10.sup.-7/.degree. C. to about 90.times.10.sup.-7/.degree.
C. Such CTE values, in addition to the reasonable maturation
temperature, allow the enamels of this invention to be applied at
workable firing temperatures with minimal thermal stresses built up
between the enamels and the glass substrate to which the product(s)
is/are applied.
[0019] Those values are comparable to established workable products
in the field as shown in the following table, which lists
Coefficient of Thermal Expansion (CTE), Glass Transition
Temperature (Tg) and Softening Point (SP) of several commercial
glasses available from Glass Coating & Concepts (GCC), Monroe,
Ohio. This table also lists the properties of a typical example of
the present invention. TABLE-US-00003 Overall CTE,
10.sup.-7/.degree. C. TG, .degree. C. SP, .degree. C. Durability GF
543* 60-85 440-448 475-495 Moderate- Weak GF 584** 65-90 440-482
480-500 Weak GF 602*** 60-85 460-495 510-535 Good Example of 65-90
490-510 530-550 Best current invention (Example 2) *GF 543,
Traditional leaded frit sold by GCC **GF-584, Lead-free,
nondurable, zinc-borosilicate glass frit sold by GCC ***GF-602,
Lead free, durable, bismuth-borosilicate glass frit sold by GCC
[0020] Those formulations of glass enamel frits are produced using
conventional techniques. Such techniques include ball milling the
melted compositions in a water solution to obtain an average
particle size of from about 3.5 microns to about 7.5 microns as
determined by a MICROTRAC.RTM. laser diffraction particle size
analyzer at a 50% range. The slurry or solution of the milled glass
frit is then dried utilizing one of the techniques that are well
known to those skilled in the art.
[0021] The glass enamel portion in this invention includes the
utilization of one or more of the glass fluxes described above in
the making of enamel to suit the intended application. An enamel
paste can be made by adding the dry flux or fluxes and other needed
pigments into a conventional screen printing medium/vehicle. The
present invention includes the utilization of other media as well.
The medium of choice depends on the particular application
technique being used. The different media include water-miscible
media, thermoplastic media, spray media, roller-coater media,
pad-transfer media, and UV-curable media. A typical example of such
a medium is one known commercially as C474 that is manufactured and
sold by GCC. Such paste is then applied to the glass substrate,
whether it is a curved container or flat substrate, via screen
printing or other application method again, such techniques are
well known to those skilled in the art. The product(s) of this
invention are suitable for various commercial glass coating
applications.
[0022] Those compositions provide improved chemical durability and
completely suitable product(s) for their intended use. For example,
the enamels herein may be used on appliance parts, including
refrigerator shelves and other appliance glassware, furniture
glass, indoor glass barriers, including satin etches for walkways,
shower doors and shower boards and the like, in glass coating
applications. Chemical durability evaluations of several acids were
done for the product(s) of this invention against both a typical
lead-free, nondurable, zinc-borosilicate glass frit sold by GCC and
a durable lead-free product commercially available from others. The
procedures mentioned next were used for the evaluations, and the
tables illustrate the results of those evaluations:
[0023] The citric and hydrochloric acid evaluations were carried
out and graded in accordance with the ASTM C724-91 test procedure.
The 0.1 N H.sub.2SO.sub.4 sulfuric acid evaluations were done by
immersion into the mentioned acid for the specified length of time.
The grading was, again, done based on the C724-91 grading scale
using the following scale: [0024] Grade 1=no attack apparent [0025]
Grade 2=appearance of iridescence or visible stain on the exposed
surface when viewed at a 45% angle, but not apparent at angles less
then 30% [0026] Grade 3=definite stain which does not blur
reflected images and is visible at angles less then 30% [0027]
Grade 4=definite stain with a gross color change or strongly
iridescent surface visible at angles less than 30% and which may
blur reflected images [0028] Grade 5=surface dull or matte with
chalking possible [0029] Grade 6=significant removal of enamel with
pinholing evident
[0030] Grade 7=complete removal of enamel in exposed area
TABLE-US-00004 Acid Type/Exposure Time 10% Citric Acid/ 3.8%
Hydrochloric Acid/ Product Type 15 minutes* 5 minutes* Commercial
high 2 2 durability lead-free frit Currently available 5 5-6 GCC
zinc-based frit** Present invention 1 1 (Example 1) *Test done
according to ASTM Test Procedure C724-91 **GF-584, lead-free,
nondurable, zinc-borosilicate glass frit sold by GCC
[0031] TABLE-US-00005 0.1 N H.sub.2SO.sub.4 Exposures at Room
Temperature Exposure Time Product Type 2 hours 24 hours 48 hours 72
hours Commercial high 1-2 3 3-4 4 durability lead-free frit
Currently available 6-7 7 7 7 GCC zinc-based frit** Present
invention 1-2 1-2 2 2 (Example 1)
[0032] It has also been discovered that utilizing frits made
according to the present invention together with other known frits
allows for use in additional applications to meet further
application requirements. Such hybrid products may be suitable for
use in, e.g., appliance applications, automotive applications, and
possibly others. The following table gives typical formulations of
example of glass enamel composition illustrating the usage of the
newly invented glass and glass flux herein. This example only
illustrates a small portion of the possibilities for such products.
The example, itself, contains three different formulations. One of
the examples also illustrates the above-mentioned fact that other
established and already made glass flux products can be added to
the product(s) of this invention to further meet certain
application requirements. TABLE-US-00006 Enamel Formulation A B C
Glass Flux 1* 96.00 50.00 Glass Flux 2** 90.00 Glass Flux 3***
10.00 Pigment (1)**** 2.50 1.00 Pigment (2)**** 8.00 36.00
Others**** 1.50 1.00 4.00 Total solids 100% 100% 100% *Flux made
according to this invention - Example 1 **Flux made according to
this invention - Example 2 ***Established flux, made by GCC - Flux
598 ****Pigments are available from Shepherd Color Company - SCC
CP-911-9B, GR0132 titania powder and SCC BL385, respectively
[0033] The present invention includes the utilization of one or
more of the glass fluxes described above in the making of enamel to
suit particular applications. An enamel paste can be made by adding
the dry flux or fluxes and other needed pigments into a
conventional screen printing vehicle. Such paste is then applied to
the glass substrate, whether it is a container or flat substrate,
via screen printing. Again, such techniques are well known to those
skilled in the art. The products of this invention are suitable for
various commercial glass coatings applications.
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